Peak UV index by city
| City | Population | Peak UV | Exposure | UV 3+ hours |
|---|---|---|---|---|
| Billings | 121,239 | 2 | Low | Below 3 all day |
| Missoula | 78,903 | 2 | Low | Below 3 all day |
| Great Falls | 60,208 | 2 | Low | Below 3 all day |
| Bozeman | 58,814 | 2 | Low | Below 3 all day |
| Butte | 35,469 | 2 | Low | Below 3 all day |
| Helena | 35,138 | 2 | Low | Below 3 all day |
| Kalispell | 31,851 | 2 | Low | Below 3 all day |
UV 3+ hours show the window from the first forecast hour at 3 or above to the end of the last. The EPA recommends sun protection at UV 3 and above. Open a city for its current-hour forecast and hourly chart. Forecast sources and limitations.
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